A building expert has expressed concerns about Auckland's historic Mt Eden Prison being empty.
Jeremy Salmond, a heritage architect of Devonport's Salmond Reed, said buildings needed to be used and it was bad for them to stand empty for long periods of time.
Mt Eden housed prisoners from about 1888, but from 2010 to 2011 the last prisoners were transferred into the new $218 million Mt Eden Corrections Facility, built alongside the Southern Motorway.
"It's very bad for any building, but especially for old buildings, to be left unoccupied," Salmond said.
"For a building that's valuable, for it to be opened up periodically, just opening all the doors and having people going through it is important" he said.